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Piezoelectric and Dielectric Properties of 0.97[(K0.5Na0.5)(Nb0.97Sb0.03)O3]-0.03[(Bi0.5K0.5)TiO3] Ceramics Modified with K5.4Cu1.3Ta10O29 (K5.4Cu1.3Ta10O29 첨가에 따른 0.97[(K0.5Na0.5)(Nb0.97Sb0.03)O3]-0.03[(Bi0.5K0.5)TiO3] 세라믹스의 압전 및 유전 특성)

  • Lee, Kab-Soo;Yoo, Ju-Hyun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.24 no.9
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    • pp.728-732
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    • 2011
  • In this study, piezoelectric and dielectric properties of Lead-free $0.97[(K_{0.5}Na_{0.5})(Nb_{0.97}Sb_{0.03})O_3]+0.03[(Bi_{0.5}K_{0.5})TiO_3]$ (abbreviated as 0.97NKNS-0.03BKT)ceramics synthesized by conventional solid-state reaction process were investigated as a function of $K_{5.4}Cu_{1.3}Ta_{10}O_{29}$ addition. The results indicated that the $K_{5.4}Cu_{1.3}Ta_{10}O_{29}$ addition significantly improved the sinterability, grain growth and piezoelctric properties of 0.97NKNS-0.03BKT ceramics. The optimum values as planar piezoelectric coupling coefficient ($k_p$= 0.355), piezoelectric constant ($d_{33}$= 207 pC/N) and mechanical quality factor ($Q_m$= 128) were obtained when 0.009KCT was added. The electromechanical coupling factor($k_p$) was slightly decreased according to the increasing temperature.

Crystal Structures, Electrical Conductivities and Electrochemical Properties of LiCo1-XMgxO2(x=0.03) for Secondary Lithium Ion Batteries (리튬 2차 전지용 LiCo1-XMgxO2(x=0.03)의 결정구조, 전기전도도 및 전기화학적 특성)

  • Kim, Ho-Jin;Chung, Uoo-Chang;Jeong, Yeon-Uk;Lee, Joon-Hyung;Kim, Jeong-Joo
    • Journal of the Korean Ceramic Society
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    • v.42 no.9
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    • pp.602-606
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    • 2005
  • [ $LiCoO_{2}$ ] is the most common cathode electrode materials in Lithium-ion batteries. $LiCo_{0.97}Mg_{0.03}O_2$ was synthesized by the solid-state reaction method. We investigated crystal structures, electrical conductivities and electrochemical properties. The crystal structure of $LiCo_{0.97}Mg_{0.03}O_2$ was analyzed by X-ray powder diffraction and Rietveld refinement. The material showed a single phase of a layered structure with the space group R-3m. The lattice parameter(a, c) of $LiCo_{0.97}Mg_{0.03}O_2$ was larger than that of $LiCoO_2$. The electrical conductivity of sintered samples was measured by the Van der Pauw method. The electrical conductivities of $LiCoO_2$ and $LiCo_{0.97}Mg_{0.03}O_2$ were $2.11{\times}10^{-4}\;S/cm$ and $2.41{\times}10^{-1}\;S/cm$ at room temperature, respectively. On the basis of the Hall effect analysis, the increase in electrical conductivities of $LiCo_{0.97}Mg_{0.03}O_2$ is believed due to the increased carrier concentrations, while the carrier mobility was almost invariant. The electrochemical performance was investigated by coin cell test. $LiCo_{0.97}Mg_{0.03}O_2$ showed improved cycling performance as compared with $LiCoO_2$.

The microwave dielectric properties of $Bi_{0.97}Tm_{0.03}NbO_{4}$ doped with $V_{2}O_{5}$ (마이크로파 유전체 $Bi_{0.97}Tm_{0.03}NbO_{4}$$V_{2}O_{5}$ 첨가에 따른 유전특성)

  • Hwang, Chang-Gyu;Jang, Gun-Eik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.350-353
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    • 2002
  • The microwave dielectric properties and the microstructures on $Bi_{0.97}Nb_{0.03}O_{4}$doped with $V_{2}O_{5}$ were systematically investigated. $Bi_{0.97}Tm_{0.03}Nb_{0.03}O_{4}$ ceramics sintered at $920-960^{\circ}C$were mainly consisted of orthorhombic and triclinic phases after addition of $V_{2}O_{5}$. The apparent density increased slightly with increasing the $V_{2}O_{5}$ addition. The dielectric $constants(\varepsilon_r)$ also increased with $V_{2}O_{5}$ addition(30-45). The $Q{\times}f_0$ values measured on $Bi_{0.97}Tm_{0.03}NbO_4$ ceramics doped with $V_{2}O_{5}$ were between 2,000 and 12,000[GHz] when the sintering temperatures are in the range of $920-960[^{\circ}C]$. It was confirmed the temperature coefficient of the resonant $frequency(\tau_f)$ can be adjusted from a positive value of $+10[ppm/^{\circ}C]$ to a negative value of $-15ppm/^{\circ}C$ by increasing the amount of $V_{2}O_{5}$. Based on our experimental results, the Bi0.97Tm0.03NbO4(added V2O5) ceramics can be applied to multilayer microwave devices at low sintering temperatures.

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Microwave dielectric properties of the $0.97MgTiO_3-0.03SrTiO_3$ ceramics with $B_2O_3$ ($B_2O_3$첨가에 따른 $0.97MgTiO_3-0.03SrTiO_3$ 세라믹스의 마이크로파 유전특성)

  • Nam, Gyu-Bin;Kim, Ji-Heon;Lee, Moon-Ki;Bae, Seon-Gi;Lee, Young-Hie
    • Proceedings of the KIEE Conference
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    • pp.94-96
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    • 2002
  • The $0.97MgTiO_3-0.03SrTiO_3$ ceramics with $B_2O_3$(10wt%) were prepared by the conventional mixed oxide method. The structural properties were investigated with sintering temperature by XRD and SEM. According to the X-ray diffraction patterns of the $0.97MgTiO_3-0.03SrTiO_3$ ceramics with $B_2O_3$(10wt%), the ilmenite $MgTiO_3$ and perovskite $SrTiO_3$ structures were coexisted and secondary phase $MgTi_2O_5$ were appeared. Increasing the sintering temperature. the grain size was increased. In the case of $0.97MgTiO_3-0.03SrTiO_3$ ceramics with $B_2O_3$(10wt%), dielectric constant, quality factor and temperature coefficient of resonant frequency were $13.52{\sim}18.13,\;32750{\sim}51736GHz$, $-15.78{\sim}25.64ppm/^{\circ}C$, respectively.

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The Microwave Dielectric Properties of Bi0.97Tm0.03NbO4 Doped with V2O5 (마이크로파 유전체 Bi0.97Tm0.03NbO4의 V2O5 첨가에 따른 유전특성)

  • 황창규;장건익;윤대호
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.11
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    • pp.975-978
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    • 2003
  • The microwave dielectric properties and the microstructures on B $i_{0.97}$T $m_{0.03}$Nb $O_4$ doped with $V_2$ $O_{5}$ were systematically investigated. B $i_{0.97}$T $m_{0.03}$Nb $O_4$ ceramics sintered at 920-96$0^{\circ}C$ were mainly consisted of orthorhombic and triclinic phases after addition of $V_2$ $O_{5}$. The apparent density increased slightly with increasing the $V_2$ $O_{5}$ addition. The dielectric constants($\varepsilon$$_{r}$) also increased with $V_2$ $O_{5}$ addition(30-45). The Q${\times}$ $f_{0}$ values measured on B $i_{0.97}$T $m_{0.03}$Nb $O_4$ ceramics doped with $V_2$ $O_{5}$ were between 2,000 and 12,000[GHz] when the sintering temperatures were in the range of 920-960[$^{\circ}C$]. It was confirmed that the temperature coefficient of the resonant frequency($\tau$$_{f}$) can be adjusted from a positive value of +10ppm/$^{\circ}C$ to a negative value of -15ppm/$^{\circ}C$ by increasing the amount of $V_2$ $O_{5}$ Based on our experimental results, the B $i_{0.97}$T $m_{0.03}$Nb $O_4$(added $V_2$ $O_{5}$) ceramics can be applied to multilayer microwave devices at low sintering temperatures.ng temperatures.emperatures.ratures.

Dielectric and Piezoelectric Properties of (K0.5Na0.5) (Nb0.97Sb0.03)O3 Ceramics Doped with K4CuNb8O23

  • Lee, Sang-Ho;Lee, Kab-Soo;Yoo, Ju-Hyun;Jeong, Yeong-Ho;Yoon, Hyun-Sang
    • Transactions on Electrical and Electronic Materials
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    • v.12 no.2
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    • pp.72-75
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    • 2011
  • In this study, $(K_{0.5}Na_{0.5})(Nb_{0.97}Sb_{0.03})O_3+0.9$ mol% $K_{5.4}Cu_{1.3}Ta_{10}O_{29}+x$ mol% $K_4CuNb_8O_{23}$ (x = 0, 0.2, 0.6, 0.8) ceramics were prepared by a conventional mixed oxide method. Their microstructure and electric properties were investigated. The secondary phase was made by virtue of $K_4CuNb_8O_{23}$ (KCN) addition in the $(K_{0.5}Na_{0.5})(Nb_{0.97}Sb_{0.03})O_3$ system ceramics. However, the sinterability of the ceramics increased with increasing $K_4CuNb_8O_{23}$ content. At the 0.6 mol% $K_4CuNb_8O_{23}$ added composition ceramics sintered at $1,060^{\circ}C$, kp and $d_{33}$ showed the optimum values of 0.39 and 145 pC/N, respectively, suitable for piezoelectric actuator application.

A study on surface photovoltage characteristics of $IN_{0.03}Ga_{0.97}AS/GaAs$ epilayer ($IN_{0.03}Ga_{0.97}AS/GaAs$에피층의 표면 광전압 특성에 관한 연구)

  • 최상수;김기홍;배인호
    • Journal of the Korean Vacuum Society
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    • v.10 no.1
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    • pp.81-86
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    • 2001
  • We have investigated surface photovoltage characteristics of InGaAs grown by metalorganic chemical vapor deposition (MOCVD) method on semi-insulating GaAs. The splitted SPV signals from the substrate and epilayer were observed. The band gap energy of InGaAs was about 1.376 eV, The In composition(x) was determined by Pan's composition formula. The photovoltage gradually decreases with increasing frequency. This is because the transfer of charge from the surface states reduces. From the temperature dependent SPV measurement, we obtained Varshni and temperature coefficients. In spectrum of etched sample at 300 K, the 'A' peak below $E_o(GaAs)$ is related with residual impurity during sample growth.

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A Study on the Phosphorescent Characteristics of Blue $\textrm{Ca}\textrm({Al}_{0.97}\textrm{B}_{0.03})_2\textrm{O}_4$: $\textrm{Eu}^{+2},\;\textrm{Nd}^{+3}$ Phosphor (청색 $\textrm{Ca}\textrm({Al}_{0.97}\textrm{B}_{0.03})_2\textrm{O}_4$: $\textrm{Eu}^{+2},\;\textrm{Nd}^{+3}$ 형광체의 잔광 특성에 관한 연구)

  • Kim, Dae-Su;Lee, Im-Ryeol
    • Korean Journal of Materials Research
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    • v.9 no.1
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    • pp.3-7
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    • 1999
  • The change of phosphorescent property with chemical modification and co-doping of Nd as an auxiliary activator in CaAl$_2$$O_4$: Eu\ulcorner, Nd\ulcorner phosphor, employing Nd\ulcornerion(0.6%) and an co-activator maintained its afterglow for 4.5 hours. And also the initial persistent brightness and phosphorescent property were further improved both by substituting Al by B atoms and incorporation of Nd\ulcorner ion. It was found that the persistent time was 30 hours for&Ca(Al_{0.97}\;B_{0.03}) $_2$$O_4$:EU\ulcorner(0.3%), Nd\ulcorner(0.6%) phosphor.

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KALIMER 98.03 설계 노심의 열수력 특성 분석

  • 김영균;김원석;김영일;박창규
    • Proceedings of the Korean Nuclear Society Conference
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    • pp.684-689
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    • 1998
  • 전기출력 150 MWe(열출력 392 MWth)의 U-Zr 이원합금핵연료 사용 소형노심인 액채금속로 KALIMER 98.03 설계 노심에 대하여 열수력 특성을 분석하고, 그 결과를 97.07 설계 노심의 열수력 설계특성과 비교.분석하였다. 분석을 위해서 냉각재 유량배분 계산에 ORFCE-F, 유량배분에 따를 온도계산에는 ORFCE-T를 사용하였는데, 이들은 현재 KALIMER 개발의 개념설계 초기 단계에서 사용하고 있는 모듈이다. 열수력 특성 분석은 먼저 각 집합체의 출력과 핵연료봉의 최고 선출력에 따라 유량그룹을 설정하고, 각 집합체의 최고온도 연료봉에 대하여 냉각재 온도, 피복관 중심온도, 핵연료 중심온도 등을 계산하는 방식으로 수행한다 열수력 특성분석 결과 98.03 설계 노심이 97.07 설계 노심에 비해 노심내 출력분포가 더욱 평탄화 되어, 노심 유량영역은 16개에서 11개로 감소되었고, 그에 따를 온도계산에서도 피복관 중심에서의 2$\sigma$ 온도가 6$65^{\circ}C$에서 628$^{\circ}C$로 낮아지는 둥 매우 향상된 설계임을 알 수 있었다.

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